[keyserver] Add Thread Invitation box to the frame

Summary:
This adds the thread invitation box to the frame image

Depends on D13985

Test Plan:
Tested on the warpcast frame validator and confirmed that the thread invitation box appeared properly

Reviewers: ashoat, varun

Reviewed By: ashoat

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D13998